In the final stages of a flat glass manufacturing operation, large sheets of glass are subdivided into a number of pieces having the desired final product dimensions. Problems have been encountered in this area due to difficulty in initiating contact between the scoring wheel and the surface of the glass precisely at the edge of the glass as they move relative to one another. The glass edge, as well as the scoring wheel, can be damaged if the scoring wheel is brought down with full force onto the edge itself or is lowered prematurely and then strikes the edge of the glass. On the other hand, if application of the full scoring force is delayed until the scoring wheel has passed over the glass some distance from the edge, the cut that is subsequently opened is often found to be defective at the end, since there was essentially no score impressed into the glass near that edge. Because of these problems, it is often necessary to trim off marginal portions of a sheet being subdivided, or to discard entire cut pieces which results in inefficient usage of each sheet. Therefore, it would be desirable if means were available for initiating a score in a sheet of glass substantially contiguous with the leading edge thereof.
This problem has been recognized in the past, but the proposed solutions have not been fully satisfactory. In U.S. Pat. Nos. 3,276,302 and 3,399,586, a roller rides onto the glass surface ahead of the scoring wheel so as to raise the scoring wheel to a predetermined scoring elevation prior to its striking the glass edge. Such arrangements may reduce the force of the impact of the scoring wheel on the glass edge but the action of the scoring wheel on the glass during the initial contact is believed to be less than a true scoring action since there is no rolling contact between the scoring wheel and the glass until the scoring wheel rebounds from the initial impact, begins passing along the upper surface of the glass, overcomes frictional forces, and then begins rotating. The result could be a substandard score in the immediate vicinity of the edge, which could lead to a defect in that region in the subsequently opened cut.